Refrigeration



July 10, 1945. J. DAVIDSON 2,380,029

REFRIGERATION Filed July 5, 1940 2 Sheets-Sheet 1 I ll INVENTOR ae/mam BY Ah ATTORNEY Sheets-Sheet 2 J. DAVIDSON REFRIGERATION Filed July 5, 1940 1 I ll 1 1 1/ 1 11 11 1 111 11 11 111111 1 1 1 1 11 1 11 1 1 11 1 111 11 1 1 1 1 11 11 1 11 1 1 1 July 10, 1945.

Patented July 10, 1945 REFRIGERATION John Davidson, Evansville, Ind., asslgnor to Servel, Inc., New York, N. Y., a corporation of Delaware Application July 5, 1940, Serial No. 343,941 1 Claim. (01. 62-125) This invention relates to refrigeration, and more particularly to a system for transferring heat to effect cooling at a region above a source of refrigeration.

It is an object of the present invention to provide a heat transfer fluid composition which is capable of improved vapor liilllid lift action. I

I have discovered that the vapor lift action of a volatile heat transfer fluid such as methyl chloride or freon is greatly improved by the presence of a small quantity of an agent having the property of increasing th viscosity of the resultant liquid, or the property of increasing the frothing and bubbling of said liquid. This agent is desirably miscible in the heat transfer fluid in order to assure circulation or return of said agent with the fluid vapor.

I have also discovered that the presence of such an agent in suflicient quantity-to materially increase the lift action of the fluid does not affect white oil.

This composition may be used in systems shown in the accompanying drawings, of which:

Fig. 1 shows more or less diagrammatically a cooling system embodying theinvention'; and

Fig. 2 similarly shows a modification of the system in Fig. 1.

Referring to Fig. 1, a primary refrigerating system has an evaporator or cooler unit I0 which is located remotely below a heat insulated region or chamber 1 l to be refrigerated, and which constitutes' a source of refrigeration for said chamber. This primary refrigerating system may be of any suitable type, as for instance a uniform pressure absorption type like that described in Patent No. 2,207,838 of A. R. Thomas. In the primary evaporator unit, a cylinder I3 is enclosed in a heat insulated shell l2 and is provided at its upper end with an annular tray l4 into which is delivered a suitable liquid refrigerant such as ammonia through a pipe IS. The ammonia is distributed from the tray l4 and flows downward over coil 26. Inert gas such as hydrogen enters the evaporator ill through pipe 16 and cylinder l3. The liquid ammonia on coil 26 evaporates and diffuses into the hydrogen, producing a refrigerating effect for cooling coil 26. The mixture of ammonia vapor and hydrogen flows from the shell 12 through the pipe I1, and is processed as described in the above patent for separate cyclic return of these fluids to-their respective inlets IS and I6. 1

A system for transferringheat from the storage chamber I l to the. primary evaporator ill includes:

a secondary evaporator unit 20 disposed. in said chamber. Evaporator 20 comprises a finned coil 22 having its upper end connected to a receiver 23. A valve M is connected between tank 23 and coil 22. Valve 24 is thermostatically operated responsive to temperature at the lower outlet end of coil 22 where a thermostat bulb 25 is located.

The evaporator 20 is connected to coil 28 form ing therewith a closed fluid circuit containing my new composition described above. Coolin of the condenser coil 26 by the action of the primary evaporator unit III will cause evaporation of liquid in the evaporator 20 and resultant coolingof the storage chamber l I. Vapor flows from evaporator 20 to the condenser coil 26' where it is cooled and condensed to liquid.

Condensed liquid flows by gravity from the condenser 28 through a pipe 23 having a trap 30 into a lift chamber 3| and the lower end of a lift conduit 32. Chamber 3| is heated by any suitable means to vaporize the liquid refrigerant therein. The entire liquid line from evaporator ID to box I I is thermally insulated, though not so illustrated for sake of clarity. By omitting insulation around chamber '3! it will be heated .This isknown as. a frost back prevention valve.

In Fig. 2 is shown a heat transfer system comprising an evaporator unit 20a disposed in a storage chamber Ila of a walk-in cooler or similar equipment and which has a plurality of finned coils 22a. supplied from a'header 23a. 'The condenser coil 26 forms with the evaporator 20a a closed fluid' circuitcontaining my new composition and is disposed below said evaporator as in the case of the system shown in Fig. 1 and has its inlet end connected to the header 23a, by a vapor line 28a.

Liquid flows by gravityfrom the condenser 26 through pipe 23, trap '30, a. filter 33, and a check valve 34 into a tube 3la. The upper end or tube 3la is connected by the riser or lift'pipe 32a tem associated with the primary evaporator unit H). Though not so shown for the sake of simplicity, the entire'liquid line from evaporator III to box I la should be thermally insulated.

Heating of liquid in the tube 3 la causes generation of vapor therein to lift the liquid through the riser or lift pipe 32a into the evaporator header 23a. I

The oil or similar agent which functions in the systems of Figs. 1 and 2 to change the viscosity of the operating liquid and/or increase the bubbling or frothing of said liquid during vapor lift action, serves to impart to the volatile liquid refrigerant a much greater lift during such action than is possible without the presence of this agent, and efl'ect this very advantageous result without any appr ciable detrimental effect upon' the refrigerating properties --of this operating liquid and also effects steady operation of the system and prompt starting from a shut-down condition. 5 v

Various changes and modifications may be made within the scope of the invention as set forth in the following claim.

What is claimed is: J r

A closed heat transfer system devoid of any moving part requiring a lubricant miscible with liquid in the system, flow of the liquid being promoted by a bubble type gas lift; and the liquid containing a minor percentage of oilwhlch increases viscosity and, therefore, frothing and hubbling of the liquid during action or the lift to increase the efliciency of such action.

J QHN DAVIDSON. 

